Titanium sponge is produced by the Kroll process, in which titanium tetrachloride is fed on a surface of molten magnesium bath preliminarily charged in a reaction vessel made of stainless steel, thereby being reduced to titanium by the molten magnesium. By bringing this titanium sponge into a vacuum separation process maintained at high temperature and reduced pressure, a highly pure titanium sponge is obtained with few magnesium chloride and magnesium metal.
Since the reduction process and vacuum separation process mentioned above are performed at a high temperature such as in a range of 900 to 1000° C., accompanied by repeatedly processing reaction batches, the reaction container tends to become gradually deformed.
In the deformation of the reaction vessel, the reaction vessel becomes deformed so that a top part of the reaction vessel comes to have “necking” (condition of increasing in length along a vertical direction and decreasing in an inner diameter) in many cases. When this deformation is promoted, the titanium sponge that is generated in the reaction vessel cannot be extracted from the reaction vessel, which is undesirable.
Therefore, it has been conducted to correct the deformation of a reaction vessel when deformation of the reaction vessel is within a permitted limit (See Japanese Unexamined Patent Application Publication No. Hei05 (1997)-212443).
In the correcting process, the deformation mentioned above, a cylinder arm equipped on a deformation-correcting apparatus that is inserted in a reaction vessel is expanded while maintaining a high temperature so as to press the reaction vessel, whereby effectively correcting the deformation of the necking deformation generated in the reaction vessel wall.
However, since the deformation-correcting operation is performed at a high temperature such as in a range from 700 to 800° C., there are problems in that it takes time and uses large amounts of electricity to heat the reaction vessel up to that temperature.
Furthermore, since the deformation-correcting apparatus itself is also exposed in a high temperature environment, a countermeasure of a heat shield and heat resistance may be necessary, and there may be cases causing problems in handling because of the heavy weight of the apparatus itself. Thus, improvement is required.
Furthermore, before starting the deformation-correcting operation, it is necessary that the deformed condition in the reaction vessel be understood in advance. From the viewpoint of operation efficiency including the operation of measuring the deformation, there is room for improvement.
In addition, it is not well-understood to what extent correcting of the deformation is appropriate in a reaction vessel that is deformed, and there are cases in which cracking of the reaction vessel wall occurs during or after deformation-correcting operation due to pressing by the deformation-correcting apparatus. Thus, improvement is required.
As explained above, an apparatus and a method for correcting the deformation thereof are required, in which deformation-correcting operation on the reaction vessel for production of titanium sponge having serious deformation can be effectively promoted.